1. What is Rainwater Tank Sizing?

Rainwater tank sizing is the process of determining the appropriate capacity for a rainwater harvesting system based on roof catchment area, local rainfall patterns, and collection efficiency.

2. How Does the Calculator Work?

The calculator uses the rainwater tank sizing formula:

Where:

• \( roof\_area\_rain\_tank \) — Roof catchment area (m²)
• \( rainfall \) — Average rainfall (mm)
• \( eff\_rain \) — Collection efficiency coefficient (dimensionless)

Explanation: The formula calculates the potential rainwater harvest by multiplying the roof area by rainfall amount and adjusting for collection efficiency.

3. Importance of Proper Tank Sizing

Details: Proper tank sizing ensures optimal water collection, prevents overflow during heavy rainfall, and provides sufficient water supply during dry periods.

4. Using the Calculator

Tips: Enter roof area in square meters, rainfall in millimeters, and efficiency coefficient (typically 0.8-0.9 for well-designed systems). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical efficiency coefficient value?
A: Efficiency coefficients typically range from 0.8 to 0.9, accounting for losses from evaporation, splash, first flush diversion, and gutter overflow.

Q2: How do I measure my roof area?
A: Calculate the horizontal projection area of your roof. For simple rectangular roofs, multiply length by width.

Q3: What rainfall data should I use?
A: Use average monthly or annual rainfall data for your location, available from meteorological services or weather stations.

Q4: Should I consider water usage in tank sizing?
A: Yes, for comprehensive sizing, also consider your water demand patterns and dry period duration in addition to collection potential.

Q5: Are there other factors to consider?
A: Yes, roof material, gutter design, filter efficiency, and local regulations may also affect your tank sizing decision.